Four days ago, it was a highway rescue story with a tragic twist — a transport truck cab engulfed in flames, with one occupant escaping but the other trapped inside, emergency workers unable to help.

Wednesday, the burned-out wreckage of the Freightliner suddenly became a focal point of a homicide investigation, with the Ontario Provincial Police charging a Brampton man with killing his wife.

What remains is the mystery of just what happened before the big rig wound up on the side of one of Ontario’s busiest super-highways, the Highway 402 east of Sarnia, its cab so badly burned it was all but obliterated in the early-morning blaze.

Tight-lipped OPP said little more Wednesday, and only confirmed the spousal relationship between the two people at the centre of the investigation after being pressed by Postmedia.

Sukhchain Singh Brar, 50, is to appear in court in Sarnia on Thursday, charged with first-degree murder in the death of 37-year-old Gurpreet K. Brar, also of Brampton, whose body police say was found in the burned vehicle.

Police wouldn’t confirm that the man and woman are the same as those seen in a photo that circulated Wednesday, with names matching those of the accused and the deceased, posted on a news web portal for India’s overseas Punjabi community

The Sukhchain Singh Brar mentioned in the Punjab Overseas post was described as an acclaimed commentator for kabaddi, a contact sport that originated in India.

Authorities were similarly guarded Sunday in the aftermath of the early-morning blaze, though it was apparent from the pile-up of investigators — the OPP’s crime unit, the regional division of the Ontario fire marshal’s office and the regional coroner — that the smouldering wreckage and the fatality were attracting more than the usual interest by authorities in a fiery highway crash.

The transport company listed on the trailer being towed by the cab could not be reached by Postmedia for comment.

The last major homicide investigation involving Hwy. 402 was more than 30 years ago, when nursing home magnate Helmuth Buxbaum of Komoka was convicted of arranging his wife’s execution — hiring a hit man to shoot her — along the highway near their London-area home.

Buxbaum died in prison in 2007 while serving a life sentence for first-degree murder.

One veteran Southwestern Ontario trucker, John Conrad, said in his 27 years of driving he’s never heard of a truck fire becoming a murder investigation. “This is a first,” the Ilderton man said.

It’s not uncommon for trucks to catch fire, said apprentice diesel mechanic Daniel Wettlaufer of Strathroy, who’s been working on big rigs for three years.

“It can happen without the driver noticing it driving down the road,” he said, adding there are “a ton of factors” that can contribute to a fire, including oil leaking on the exhaust system and brakes dragging.

Londoner Martin Stark, a retired trucker who drove for 45 years, said it’s not unheard of for truckers to wake up in their bunk at the side of the road to a cab filled with smoke.

“It’s very common, especially with a truck that’s had some work done on it,” he said.

The chief of the Wyoming fire department, which responded to the blaze, could not be reached Wednesday.